This is a bug in Unix culture and an example of spray-on usability. It's perfectly legal to have a file named "Software Manager" and it's not even harder to type if your shell has case-insensitive completion. Yet the situation persists where the "human-readable name" is different from the "internal name". (Not that people generally launch GUI apps from the command line anyway.)

Calling an executable "Software Manager" is legal, but it's also inconsistent with other executables.

In this case the executable is "mintinstall" and it could have been called software-manager or softwaremanager.

You are right, the human readable name is generally different from the internal name, but the internal name should be invisible to a GUI user.

Here the problem is that the name of the executable has made its way to the GUI.